Then there are a few items you will not find in the BMW manual, but will find in the Daddy manual,

Order a bottle or two each of Lexol Orange (leather cleaner) & Brown (leather conditioner) and 2 new seat protectors (the ones that go under the baby car seats to protect the leather...

and plan to spend about 2 hours with rags and a Shop-Vac cleaning out the muck left by Kid #1. By the time Kid #2 arrived, I ended up ordering new seat covers from Britax for Kid #1's seat.